Phase 2 Data Shows Novel Kinase Inhibitor Significantly Improves PFS in Advanced Breast Cancer

Share this content:

Pfizer announced randomized Phase 2 data that showed PD-0332991 (PD-991) in combination with letrozole (Femara; Novartis) significantly extended progression free survival (PFS) compared with letrozole alone in post-menopausal patients with estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-) locally advanced or metastatic breast cancer. PD-991 is an investigational, oral and selective inhibitor of the CDK 4 and 6 kinases.

A total of 66 patients were enrolled in Part 1 of the study. Preliminary results of Part 1, announced in May 2012, showed statistically significant improvement in median PFS in the PD-991 plus letrozole arm vs. the letrozole arm. Part 2 enrolled 99 additional patients whose tumors were selected for presence of biomarkers: cyclin D1 amplification and/or p16 loss. The results announced today reflect the combined interim data analysis of Parts 1 and 2.

For patients treated with the combination of PD-991 plus letrozole, median PFS was 26.1 months, a statistically significant improvement compared to the median PFS in women who received letrozole alone, which was 7.5 months (HR=0.37 [95% CI: 0.21, 0.63]; P<0.001). In patients with measurable disease, the objective response rate was 45% for those women who received PD-991 plus letrozole vs. 31% for those who received letrozole alone. The clinical benefit rate (defined as complete response plus partial response plus stable disease for ≥24 weeks) was 70% vs. 44%, respectively. The differences observed in the objective response rate and clinical benefit rate were statistically significant.

For more information call (800) 438-1985 or visit

Related Resources

You must be a registered member of Cancer Therapy Advisor to post a comment.

Sign Up for Free e-newsletters

Regimen and Drug Listings


Bone Cancer Regimens Drugs
Brain Cancer Regimens Drugs
Breast Cancer Regimens Drugs
Endocrine Cancer Regimens Drugs
Gastrointestinal Cancer Regimens Drugs
Gynecologic Cancer Regimens Drugs
Head and Neck Cancer Regimens Drugs
Hematologic Cancer Regimens Drugs
Lung Cancer Regimens Drugs
Other Cancers Regimens
Prostate Cancer Regimens Drugs
Rare Cancers Regimens
Renal Cell Carcinoma Regimens Drugs
Skin Cancer Regimens Drugs
Urologic Cancers Regimens Drugs